The program is directed at structural studies of macromolecules from higher reso lution data on proteins in the form of single crystals to the larger scale geome try presently assessable in organelles such as ribosomes and plasma membranes. The techniques to be employed center on diffraction and low angle solution scat- tering of both X-rays and neutrons. In addition to the time-average structures, which are the most immediate output of such work, the program will be particular ly aimed at studying the motion of various parts of the polymer chains and of subunits with respect to each other in the larger aggregates. Of special inter- est is the motion of specific side chains during catalytic cycles, of the poly- merase class of enzymes along the nucleic acid chains, and the translocation ste of ribosomes on the message during protein synthesis. The control of these pro- cesses by specific ligands will be investigated. The studies will combine both experimental and theoretical approaches to these problems.